Conventionally, there has been known a substrate processing apparatus that processes a substrate, such as a semiconductor wafer or a glass substrate, by supplying a processing liquid through a nozzle.
The processing liquid may adhere to the nozzle and may remain at the nozzle as a cohesive material. If a substrate process is performed while such a cohesive material adheres to the nozzle, the cohesive material adhering to the nozzle may be scattered on the substrate, so that the substrate is damaged. Therefore, such a substrate processing apparatus may include a nozzle cleaning device configured to clean the nozzle with a cleaning liquid to remove the cohesive material adhering to the nozzle.
By way of example, Patent Document 1 describes a nozzle cleaning device configured to inject a cleaning liquid to a nozzle from one side of the nozzle to remove a cohesive material adhering to the nozzle.
Further, Patent Document 2 describes a nozzle cleaning device that includes a cleaning chamber configured to accommodate a nozzle and is configured to supply a cleaning liquid along an inner peripheral surface of the cleaning chamber and form a vortex-shaped flow of the cleaning liquid around a front end of the nozzle to clean the front end of the nozzle.
Patent Document 1: Japanese Patent Laid-open Publication No. 2007-258462
Patent Document 2: Japanese Patent Laid-open Publication No. 2007-317706
However, if the cleaning liquid is injected as described in Patent Document 1, the nozzle may not be cleaned uniformly. In particular, if the cleaning liquid is injected from one side of the nozzle as described in Patent Document 1, the other side of the nozzle cannot be cleaned sufficiently.
Further, in accordance with the method as described in Patent Document 2, an upper part of the nozzle may not be cleaned. This is because if the upper part of the nozzle is cleaned by the cleaning liquid stored in the cleaning chamber, the cleaning liquid may overflow a storage tank.